1. Field of the Invention
The present invention relates to relays and, more particularly, to a MEMS relay that has a flux path from magnetic actuation that is decoupled from an electrical path through the switch, and a suspension structure that is independent of the core structure, and a method of forming the same.
2. Description of the Related Art
A switch is a well-known device that connects, disconnects, or changes connections between devices. An electrical switch is a switch that provides a low-impedance electrical pathway when the switch is “closed,” and a high-impedance electrical pathway when the switch is “opened.” A mechanical-electrical switch is a type of switch where the low-impedance electrical pathway is formed by physically bringing two electrical contacts together, and the high-impedance electrical pathway is formed by physically separating the two electrical contacts from each other.
An actuator is a well-known mechanical device that moves or controls a mechanical member to move or control another device. Actuators are commonly used with mechanical-electrical switches to move or control a mechanical member that closes and opens the switch, thereby providing the low-impedance and high-impedance electrical pathways, respectively, in response to the actuator.
A relay is a combination of a switch and an actuator where the mechanical member in the actuator moves in response to electromagnetic changes in the conditions of an electrical circuit. For example, electromagnetic changes due to the presence or absence of a current in a coil can cause the mechanical member in the actuator to close and open the switch.
One approach to implementing actuators and relays is to use micro-electromechanical system (MEMS) technology. MEMS devices are formed using the same fabrication processes that are used to form conventional semiconductor structures, such as the interconnect structures that provide electrical connectivity to the transistors on a die.
One drawback of conventional MEMS relays is that the flux path that actuates the device also typically follows the electrical path through the switch. Traditionally, relays are used for power switching, and thus signal attenuation through the switch due to fluctuations in the current around the core and, thereby the flux, has not been a concern.
However, when MEMS relays are passing signals with very small amplitudes through the switch, fluctuations in the current around the core and, thereby the flux, can lead to an unacceptable degradation of the signal passing through the switch. Thus, there is a need for a MEMS relay that has a flux path that is decoupled from the electrical path through the switch.
Another drawback of conventional MEMS relays is that the suspension structure is typically formed as part of the core structure. The suspension and core structures, however, commonly have conflicting requirements. The ideal geometry of the core structure is a short flux path with a large cross-sectional area. However, the ideal geometry of the suspension structure is a long path with a small cross-sectional area because this reduces the spring stiffness of the beam, and thus the force required to close the switch. Thus, there is also a need for a MEMS relay that has a suspension structure that is independent of the core structure.